Flat or spade type wood boring bit



Feb. 26, 1957- C. J. ROBINSON FLAT 0R SPADE TYPE WOOD BORING BIT Filed April 27, 1954 Clarence J. Robinson INVENTOR ATTORNEY! FLAT OR SPADE TYPE WOOD BORING BIT Clarence J. Robinson, Wilmington, Ohio, assignor to The Irwin Auger Bit Company, Wilmington, Ohio, a corporation of Ohio Application April 27, 1954, Serial No. 425,915

1 Claim. (Cl. 145-116) This invention relates to woodworking tools and more particularly to flat or spade type wood boring bits, generally employed in a hand-held electric drill or drill press.

An important object of the invention is to provide a bit of this character which requires less torque and thrust in operation than do conventional bits for the purpose mentioned.

Another important object is to provide a bit as described in which the cutting angle at the cutting edge of the point is lessened over that of conventional bits of this character, whereby an appreciable reduction in thrust and torque is achieved.

Other objects and advantages of the invention will be apparent during the course of the following detailed description of the invention, taken in connection with the accompanying drawing, forming a part of this disclosure, and in which drawing:

Fig. l is an elevation of a flat or spade type wood boring bit disclosing one form of the invention.

Fig. 2 is an enlarged horizontal section of the point of the bit of Fig. l, substantially on the line 2-2 of Fig. 1.

Fig. 3 is a horizontal section of the point (enlarged) of a bit differing from that of Figs. 1 and 2 only in the shape of the flutes or grooves.

Fig. 4 is an elevation of a flat or spade type wood boring bit disclosing another form of the invention in which the flutes or grooves are angular.

Fig. 5 is an enlarged horizontal section of the point of the bit of Fig. 4, substantially on the line 5-5 of Fig. 4.

Fig. 6 is a horizontal section of the point (enlarged) of a bit differing from that of Figs. 4 and 5 only in the shape of the flutes or grooves.

Fig. 7 is an enlarged horizontal section of the point of a conventional flat or spade type wood boring bit.

In the drawing, wherein for the purpose of illustration are shown several embodiments of the invention and wherein similar reference characters designate corresponding parts throughout the several views, the letters A, B, C and D designate four embodiments of the invention and E, a conventional flat or spade type wood boring bit.

Each embodiment of the invention comprises a shank, a blade, and a point. Except for the point, each bit is substantially alike.

In the embodiment A of Figs. 1 and 2, the shank 10 is shown as a cylindrical body portion with the free end portion reduced in circumference to provide the shoulder 11 and this portion is provided with a plurality of spaced-apart flats 12, for the chuck jaws, all this being conventional construction.

The blade 13 extending from the inner end portion of the shank and is preferably integral therewith, and comprises a body portion having opposite, substantially flat faces and bevelled edges or faces 14, 15, 16 and 17, with Tnited States Patent'O 2,782,824 Patented Feb. 26, 1957 ICC the edges or faces 15 and 16 being terminal edges with the bevelled faces extending in opposite directions, as can be appreciated in Fig. 1, but the bevels of the edges or faces 14 and 17 extend substantially parallel.

The point 18 extends from the outer end of the body portion of the blade 13 and is preferably integral therewith. It comprises a body portion having a thickness substantially like that of the blade 13 and bevelled end edges or faces 19 and 20 with the edge 20 like the edge 19.

Extending from the apex 21 of the body portion of the point 18 is a groove or flute 22 in each opposite flat side face of the body portion of the point body. Each groove or flute 22 is defined by opposite longitudinal edges 23 and 24 insubstantial parallelism, while one edge 24 is also an edge of the bevelled face 20. Edges 23 and 24 join each other at a location in the body portion of the blade 13 just inwardly of the edges 15 and 16 respectively. It will be noted, in Fig. 2, that the grooves or flutes 22 are arcuate transversely.

The embodiment B differs from A simply in the transverse contour of the flutes or grooves 25 of the point 26 of the embodiment B, since they are curved transversely at the face 27 from the longitudinal edge 28 of the flute or groove and they then have substantially flat faces 29 joining the faces 27 and extending to the longitudinal edge 30. The longitudinal edges 28 and 30 join to form a juncture quite similar to that of the edges 23 and 24.

In Figs. 4, 5 and 6 are shown the embodiments C and D of the invention. They too differ from the embodiment A simply in the transverse contour of their flutes or grooves as well as the shape of the junctures of the longitudinal edges of these flutes or grooves.

In Fig. 5 it will be seen that each of the flutes or grooves 31 of the point 32 of the embodiment C, have two substantially flat faces 33 and 34 with the face 33 extending from the longitudinal edge 35 and the face 34 extending from the opposite edge 36 and these edges come together in a point 37 in the body portion of the blade 44. It will be noted that the edges 35 also form one edge of each of the bevelled end faces of the body of the point 32.

In Fig. 6 which is a section of the point 38 of the embodiment D, the flutes or grooves 39 each have substantially flat faces 40 and 41 with the face 40 extending from the edge 42 and the face 41 extending from the edge 43.

In Fig. 7 there is shown, by way of example, and for comparison, a horizontal cross section of the body of a point 45 of a conventional flat or spade type Wood boring bit E, having unbroken flat faces 46 and 47, bevelled edges end edges or faces 48 and 49 and cutting edges 50 and 51. Comparison thereof with any of Figs. 2, 3, 5 or 6 will show the sharper cutting edges 24, 30, 35 and 42 of the fiat or spade type wood boring bits of this invention. As a consequence, the sharper edges of the points 18, 26, 32 and 38 enable these points to penetrate wood with a less expenditure of energy and thrust than would be the case when the conventional point 45 of Fig. 7 is employed in penetrating the same kind of wood.

I prefer to forge the bits of this invention from solid or integral pieces of steel, with heat treatment all over, and have discovered that, despite the provision of the flutes or grooves, which are preferably milled or hollow ground, the bits are sturdy and will not bend.

In order to permit hanging of the bits upon a support, as a nail, I prefer to provide a small perforation, like the openings 52 or 53 in the blades of the bits to receive the shank of the nail.

In the use of the new bits of this invention, a hole may be drilled in wood by the combined action of the torque of a small, inexpensive power drill and thrust imparted by the operator. points of these bits are sharper and hence, are easier to use, and there are provided the flutes extending to the fiat side faces of the blade, the chips which are only a few thousandths of an inch thick, travel along the flutes and are discharged over the wide flat side faces of the blade and into the pockets defined by these faces and the walls of the hole drilled by the bit blade.

Various changes may be made to the forms of the invention herein shown and described without departing from the spirit of the invention or scope of the claim.

What is claimed is:

A spade type wood boring bit having a flattened blade body portion provided with substantially parallel side faces and bevelled edges joining said side faces, said bevelled edges including an end edge, and a point extending outwardly from said flattened blade body portion, said point comprising a point body portion terminating in an apex and having a pair of substantially parallel side faces and narrow bevelled edges joining the lastnamed side faces and extending to said end edge intermediate the ends of said end edge, each side face of said point body portion being provided with a longitudinally inclined elongated flute partly defined by two elongated Since the cutting edges of the substantially parallel edges on said point body portion, with one of said elongated substantially parallel edges extending from the apex of the point body portion toward the juncture of the blade body portion and point body portion and the other of said elongated substantially parallel edges extending, from a location at one of said narrow bevelled edges intermediate said apex and said end edge, toward the juncture of the blade body portion and point body portion, and the juncture of the other of said narrow bevelled edges and one side face of said point body portion providing a cutting edge.

References Cited in the file of this patent UNITED STATES PATENTS 222,101 Temple Nov. 25, 1879 777,543 Rich Dec. 13, 1904 1,017,352 Wagner Feb. 13, 1912 1,047,466 Wagner Dec. 17, 1912 2,354,985 Davis Aug. 1, 1944 2,543,206 Smith Feb. 27, 1951. 2,689,131 Priest Sept. 14, 1954 FOREIGN PATENTS 523,724 Germany Apr. 27, 1931 443,192 France July 8, 1912 

